Disk drives are information storage devices that use magnetic media to store data and a movable read/write head positioned over the magnetic media to selectively read data from and write data to the magnetic media.
Consumers are constantly desiring greater storage capacity for such disk drive devices, as well as faster and more accurate reading and writing operations. Thus, disk drive manufacturers have continued to develop higher capacity disk drives by, for example, increasing the recording and reproducing density of the information tracks on the disks by using a narrower track width and/or a narrower track pitch. However, each increase in track density requires that the disk drive device have a corresponding increase in the positional control of the read/write head in order to enable quick and accurate reading and writing operations using the higher density disks. As track density increases, it becomes more and more difficult to quickly and accurately position the read/write head over the desired information tracks on the disk. Thus, disk drive manufacturers are constantly seeking ways to improve the positional control of the read/write head in order to take advantage of the continual increases in track density. At present, various open literatures have disclosed ways of positional control of the read/write head, for example, U.S. Patent No. 2003-0168935, entitled “Piezoelectric Driving Device”.
One approach that has been effectively used by disk drive manufacturers to improve the positional control of read/write heads for higher density disks is to employ a voice coil motor (VCM). Referring to FIG. 1a, a conventional disk drive device using VCM typically has a drive arm 104, a HGA 106 attached to and mounted on the drive arm 104, a stack of magnetic disks 101 suspending the HGA 106, and a spindle motor 102 for spinning the disks 101. The employed VCM is denoted by reference number 105 and is connected to the drive arm 104 for controlling the motion of the drive arm 104 and, in turn, controlling a slider 103 of the HGA 106 to position with reference to data tracks across the surface of the magnetic disk 101, thereby enabling the read/write head imbedded in the slider 103 to read data from or write data to the disk 101. However, because the inherent tolerances of the VCM 105 and the HGA 106 exist in the displacement of the slider 103 by employing VCM 105 alone, the slider 103 cannot achieve quick and fine position control which adversely impacts the ability of the read/write head to accurately read data from and write data to the disk 101.
In order to solve the problem, an additional actuator, for example a PZT micro-actuator, is introduced in the disk drive device in order to modify or fine tune the displacement of the slider 103. The PZT micro-actuator corrects the displacement of the slider 103 on a much smaller scale, as compared to the VCM, in order to compensate for the resonance tolerance of the VCM and/or the HGA. The micro-actuator 105 enables, for example, the use of a smaller recording track pitch, and can increase the “tracks-per-inch” (TPI) value by 50% for the disk drive unit, as well as provide an advantageous reduction in the head seeking and settling time. Thus, the PZT micro-actuator enables the disk drive device to have a significant increase in the surface recording density of the information storage disks used therein.
Referring to FIGS. 1a and 1b, the PZT micro-actuator has two PZT elements denoted by reference number 107 and mounted within the HGA 106 which further includes the slider 103 and a suspension 110 to support the slider 103 and the PZT elements 107 of the micro-actuator. The suspension 110 comprises a flexure 111, a slider support 112 with a bump 112a formed thereon, a metal base 113 and a load beam 114 with a dimple 114a formed thereon for supporting the slider support 112 and the metal base 113. The slider 103 is partially mounted on the slider support 112 with the bump 112a supporting the center of the back surface of the slider 103. Specifically, the flexure 111 provides a plurality of traces thereon. The traces of the flexure 111 couple the slider support 112 and the metal base 113. The flexure 111 further forms a tongue region 111a for positioning the two PZT elements 107 of the micro-actuator. Referring to FIG. 1c, when a voltage is input to the two thin film PZT elements 107 of the PZT micro-actuator, one of the PZT elements may contract as shown by arrow D while the other may expand as shown by arrow E. This will generate a rotation torque that causes the slider support 112 to rotate in the arrowed direction C and, in turn, makes the slider 103 move on the disk. In such case, the dimple 114a of the load beam 114 works with the bump 112a of the slider support 112, that is, the slider 103 together with the slider support 112 rotates against the dimple 114a, which keeps the load force from the load beam 114 evenly applying to the center of the slider 103, thus ensuring the slider 103 a good fly performance, supporting the head with a good flying stability.
However, as the slider support 112 is coupled with the metal base 113 by the traces of the flexure 111 which are only 10-20 um in thickness and formed from soft polymer material, the flexure 111 is easy to distort and accordingly the suspension 110 is likely to deform during the suspension manufacture process, HGA manufacturing process, the handle process or ultrasonic cleaning process. Such deformation also happens in case of vibration or a shock event. Moreover, the suspension deformation resulted from such weak structure will adversely cause the suspension or HGA dimple separation. FIGS. 2a and 2b respectively show a suspension tongue region deformation and a dimple separation. Besides, as the slider 103 is partially mounted on the slider support 112 and the slider support 112 is coupled with the metal base 113 via traces of the flexure 111, the static attitude of the slider 103 such as PSA (pitch static attitude) or RSA (roll static attitude) is difficult to control, which causes the HGA performance unstable and accordingly, affects the HGA dynamic performance seriously, especially when a vibration or shock event happens or during the manufacture process or handle process. Finally, such structure makes the whole HGA a poor shock performance. When a vibration or shock event happens, for example tilt drop shock or operation shock, the suspension 110 or the PZT elements 107 of the PZT micro-actuator may be caused to damage.
Hence, it is desired to provide an improved suspension, a HGA with a micro-actuator and its manufacturing method, and a disk drive unit with such HGA to solve the above-mentioned problems and achieve a good performance.